This invention relates to a sealant composition for use in subterranean formations and, in specific examples, sealant compositions that may be used for creating fluid flow preventing barriers in a subterranean formation.
When hydrocarbons are produced from wells that penetrate hydrocarbon producing formations, water often accompanies the hydrocarbons, particularly as the wells mature in time. The water can be the result of a water producing zone communicated with the hydrocarbon producing formations or zones by fractures, high permeability streaks and the like, or the water can be caused by a variety of other occurrences which are well known to those skilled in the art, such as water coning, water cresting, bottom water, channeling at the wellbore, etc. As used herein, the term “zone” simply refers to a portion of the formation and does not imply a particular geological strata or composition. Over the life of such wells, the ratio of water to hydrocarbons recovered may be undesirable in view of the cost of producing the water, separating it from the hydrocarbons, and disposing it, which can represent a significant economic loss.
A variety of techniques have been used to reduce the production of undesired water. Generally, these techniques involve the placement of a material in a wellbore penetrating a water-bearing portion of a subterranean formation that may prevent or control the flow of water into the wellbore. The techniques used to place these materials are referred to herein as “conformance techniques” or “conformance treatments.” Some techniques involve the injection of particulates, foams, gels, sealants, or blocking polymers into the subterranean formation so as to plug off the water-bearing portions. For example, squeeze cementing techniques may be used wherein a cement slurry is forced with pressure into a void or channel through which water would otherwise flow into the wellbore, and the cement is allowed to set and seal off that channel. In other techniques, polymers referred to as “relative permeability modifiers” recently have been used, in some instances, to decrease the proportion of water with produced hydrocarbons.